• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.67-75
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• 2009

Multi-layered video coding that provides scalability across the visual content has emerged for easily adaptive service over current heterogeneous network. However, the network is still error prone environment so that video service may suffer packet loss or erroneous decoding of the video. Especially distortion caused by the burst error may propagate to several pictures until intra refreshing, which will raise a terrific degradation of picture quality. To overcome the problem at terminal independently, we propose a new error concealment algorithm for the multi-layered video coding. The proposed method uses the similarity of between layers in the multi-layered video coding and POCS (Projections Onto Convex Sets) which is a powerful error concealment tool, but heavily dependent on initial values. To find adequate initial value which can reduce iteration times as well as achieve high performance, we took consideration into both features of layered approach coding and the correlation in neighbor blocks. The simulation results show that the proposed concealment method works well.

• Journal of the Korea Society of Computer and Information
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• v.15 no.5
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• pp.57-65
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• 2010

In this paper, we propose a new real-time algorithm detecting the flame and smoke in digital CCTV images. Because the forest fire causes the enormous human life and damage of property, the early management according to the early sensing is very important. The proposed algorithm for monitoring forest fire is classified into the flame sensing and detection of smoke. The flame sensing algorithm detects a flame through the conditional test at YCbCr color model from the single frame. For the detection of smoke, firstly the background range is set by using differences between current picture and the average picture among the adjacent frames in the weighted value, and the pixels which get out of this range and have a gray-scale are detected in the smoke area. Because the proposed flame sensing algorithm is stronger than the existing algorithms in the change of the illuminance according to the quantity of sunshine, and the smoke detection algorithm senses the pixel of a gray-scale with the smoke considering the amount of change for unit time, the effective early forest fire detection is possible. The experimental results indicate that the proposed algorithm provides better performance than existing algorithms.

• Korean Journal of Plant Resources
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• v.21 no.5
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• pp.357-361
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• 2008

The photosynthetic characteristics of three Ligularia species, L. fischeri, L. fischeri var. spiciformis and L. stenocephala under-tree cultivated in Dunnae-myeon, Hoengsung-gun were measured and compared. Total mean photosynthetic rate increased with increasing the light intensity up to 2,000 PPFD. Mean photosynthetic rate of L. fischeri increased to maximum value of $21.1{\mu}mol\;CO_{2}m^{-2}s^{-1}$ with increasing the light intensity up to 1,600 PPFD, but it was decreased at 2,000 PPFD. The highest photosynthetic rate was shown in L. fischeri var. spiciformis, followed by L. fischeri, and L. stenocephala. was the highest $27.39{\mu}mol\;CO_{2}m^{-2}s^{-1}$ among three species, followed by that of The differences in photosynthetic rates were significantly different among the species each measuring date. L. fischeri var. spiciformis was more adaptive species at the low elevated under-tree cultivated sites, such as, Sanchemaeul Dunnae-myeon Hoeyngseung-gun than L. fischeri and L. stenocephala.

• Korea Journal of Hospital Management
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• v.4 no.1
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• pp.21-40
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• 1999

This study attempts to analyze the relationship between various job-related factors and the intent to turnover of employees working at different types of hospitals/clinics in urban and rural areas. The data was compiled from 1,506 employees in 21 hospitals and 10 clinics located in Kyung-gi Do. Korea, using a self-administered questionnaire. Major findings are as follows: 1) The intent to turnover was higher for the employees of small hospitals located in rural areas. It was also higher when the employees were less than 30 in age, female, single, had not received college education, and had worked for 2-5 years in their hospitals. 2) An important factor affecting the intent to turnover was job satisfaction, which in turn had a strong correlation with the job itself(opportunity of utilizing abilities and skills, subjective value attached to the current job, sense of accomplishment) and had a rather weak correlation with salary, supervision, promotion and co-worker relationship. 3) In the analysis by job category, it was found that, besides job satisfaction, the intent to turnover was significantly affected by the job itself in case of administrative personnel and by the level of salary in case of nurses. 4) For a successful management of turnover, hospitals need to develop (a) programs for improving adaptive abilities of 'new' employees(who have worked for less than 2 years), and (b) for the other employees(who have worked for more than 2 years), strategies for enhancing job satisfaction by providing the environment where they can show their maximum abilities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.670-675
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• 2018

There is a growing interest in EH-WSN (energy-harvesting wireless sensor networks) that can solve power problems in wireless sensor networks. In EH-WSN, on-off duty cycling is being studied in order to balance energy harvesting and consumption. However, the urgency of the sensed data and the energy harvesting rate in the environmental monitoring EH-WSN are important factors to determine the network performance. Therefore, it is necessary to control the duty-cycle period according to the importance of the sensed data and the energy harvesting rate in addition to simply maintaining the balance of the power. In this paper, we analyze the problem of on-off duty cycling in EH-WSN for environmental monitoring and propose an adaptive duty-cycle scheduling scheme considering the priority of sensed data and energy harvesting rate, where the priority of sensed data determined by sensed value and changing rate. The performance of scheduling scheme was analyzed by computer simulations.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.206-217
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• 2018

We develop the signal processing method for adaptive implementing direction of signal and the frequency sensitivity of human visual system(HVS). Existing multiband energy scaling method makes ringing artifact because it does not consider signal direction. To solve this problem, we use block gradient for signal direction in addition to existing method. And we use the fact that frequency component of signal is more sensitive than value of signal over human eyes. we enhance the signal according to contrast sensitivity function(CSF) which is the model of frequency sensitivity of human eye. Compared that the existing analysis models only improve the efficiencies in the existing systems, the developed method can process the image signals to be more desirable and suitable to HVS.

• Journal of Power Electronics
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• v.18 no.1
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• pp.234-250
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• 2018

This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.763-770
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• 2002

Recognition of CW Morse signals can be divided into several phases such as detection of tones and spaces, signal processing for removing noise from detected signals, decision of tones/spaces, mapping a sequence of tones and spaces into characters, error correction of a character message with textual repetition. In this paper, in order to cope with signal fading effectively we propose a signal detection method of identifying peaks in the frequency domain and present techniques for combining multiple frequency peaks and for removing residual signal components and noise. LMS adaptive method is applied for decision of tones/spaces, and initial value setting and malfunctioning conditions are analyzed. In recognition experiments, we used CW Morse signals collected by radio receivers and found that the proposed method achieves good recognition performance even in severe fading conditions.

• The Journal of the Korea Contents Association
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• v.3 no.2
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• pp.11-18
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• 2003

In this paper, we propose a fast variable block matching algorithm for motion estimation based on bit-patterns. Motion estimation in the proposed algorithm is peformed after the representation of image sequence is transformed 8-bit pixel values into 1-bit ones by the mean pixel value of search block, which brings a short searching time by reducing the computational complexity. Moreover, adaptive searching methods according to the motion information of the block make the procedure of motion estimation efficient by eliminating unnecessary searching processes of low motion block and deepening a searching procedure in high motion block. Experimental results show that the proposed algorithm provides bettor performance - average 0.5dB PSNR improvement and about 99% savings in the number of operations - than full search Hock matching algorithm with a fixed block size.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.11
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• pp.549-560
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• 2001

Cluster system provides attractive scalability in terms of compution power and memory size. With the advances in high speed computer network technology, cluster systems are becoming increasingly competitive compared to expensive MPPs (massively parallel processors). Load balancing is very important issue since an inappropriate scheduling of tasks cannot exploit the true potential of the system and can offset the gain from parallelization. In parallel processing program, it is difficult to predict the load of each task before running the program. Furthermore, tasks are interdependent each other in many ways. The dynamic load balancing algorithm, which evaluates each processor's load in runtime, partitions each task into the appropriate granularity and assigns them to processors in proportion to their performance in cluster systems. However, if the communication cost between processing nodes is expensive, it is not efficient for all nodes to attend load balancing process. In this paper, we restrict a processor that attend load balancing by the communication cost and the deviation of its load from the average. We simulate various models of the cluster system with parameters such as communication cost, node number, and range of workload value to compare existing load balancing methods with the proposed dynamic algorithms.